Quote an authority is a phrase that is used to refer to the practice of citing an expert or authoritative source when making a statement. CITE, in this context, means to quote or refer to a source for support or evidence. Speakbythebook is a phrase that suggests that one should speak with authority and accuracy, as if they are quoting from a book. This phrase implies that one should be well-informed and knowledgeable about the topic they are discussing.